CVE-2025-27936: Github.com/mattermost/mattermost/server/v8 Mattermost Vulnerable To Observable Timing Vulnerability
MODERATECVE-2025-27936 is a MODERATE (CVSS 5.3) mattermost vulnerable to observable timing vulnerability (CWE-208: Observable Timing Discrepancy) affecting Github.com/mattermost/mattermost/server/v8 libraries in the Go ecosystem. The issue involves mattermost vulnerable to observable timing discrepancy. Remediation is available by upgrading affected packages to version 10.5.2, 8.0.0-20250314142426-c049748b8863, 2.1.0.
CVE-2025-27936 at a Glance
Security Impact
CVSS: 5.3
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N).
How to Fix CVE-2025-27936
To remediate this vulnerability, upgrade all affected Github.com/mattermost/mattermost/server/v8 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/mattermost/mattermost/server/v8 to 10.5.2Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20250314142426-c049748b8863Upgrade github.com/mattermost/mattermost-plugin-msteams to 2.1.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/mattermost/mattermost/server/v8How to Check if You Are Affected
To determine whether your application is affected by CVE-2025-27936, inspect your project dependencies for Github.com/mattermost/mattermost/server/v8:
inspect dependencies for github.com/mattermost/mattermost/server/v8Analyze the terminal output to locate any version of Github.com/mattermost/mattermost/server/v8 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.5.2), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-208: Observable Timing Discrepancy, where two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. In Github.com/mattermost/mattermost/server/v8, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2025-27936 Affected Github.com/mattermost/mattermost/server/v8 Versions
3 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/mattermost/mattermost/server/v8
|
Go |
≥ 10.5.0
< 10.5.2
|
10.5.2
|
|
github.com/mattermost/mattermost/server/v8
|
Go |
< 8.0.0-20250314142426-c049748b8863
|
8.0.0-20250314142426-c049748b8863
|
|
github.com/mattermost/mattermost-plugin-msteams
|
Go |
< 2.1.0
|
2.1.0
|
References
Frequently Asked Questions
What is CVE-2025-27936?
Which Github.com/mattermost/mattermost/server/v8 versions are affected?
What version fixes CVE-2025-27936?
Is github.com/mattermost/mattermost/server/v8 affected?
Is github.com/mattermost/mattermost-plugin-msteams affected?
What is the CVSS score of CVE-2025-27936?
What CWE is associated with CVE-2025-27936?
How can I check Go dependencies for CVE-2025-27936?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-2j87-p623-8cc2",
"modified" : "2025-04-23T15:18:35Z",
"published" : "2025-04-16T12:31:19Z",
"aliases" : [ "CVE-2025-27936" ],
"summary" : "Mattermost vulnerable to Observable Timing Discrepancy",
"details" : "Mattermost Plugin MSTeams versions <2.1.0 and Mattermost Server versions 10.5.x <=10.5.1 with the MS Teams plugin enabled fail to perform constant time comparison on a MSTeams plugin webhook secret which allows an attacker to retrieve the webhook secret of the MSTeams plugin via a timing attack during webhook secret comparison.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/mattermost/mattermost/server/v8"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "10.5.0"
}, {
"fixed" : "10.5.2"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/mattermost/mattermost/server/v8"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "8.0.0-20250314142426-c049748b8863"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/mattermost/mattermost-plugin-msteams"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.1.0"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 1.15.0"
}
} ],
"references" : [ {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-27936"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/mattermost/mattermost"
}, {
"type" : "WEB",
"url" : "https://mattermost.com/security-updates"
}, {
"type" : "WEB",
"url" : "https://pkg.go.dev/vuln/GO-2025-3618"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-208" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2025-04-16T14:58:55Z",
"nvd_published_at" : "2025-04-16T10:15:14Z"
}
}